#include <iostream>

using namespace std;

class person {
	public:
		int m_Age;
		mutable int m_Age2;
		void fun1() const {

		}

		void fun2() {
			m_Age = 100;
		}
};

int main() {
	person p1;
	p1.m_Age = 20;
	p1.fun1();
	cout << p1.m_Age << endl;

	const person p2;
//	p2.m_Age = 18;
//	p2.fun2();
	p2.fun1();
	cout << p2.m_Age << endl;

	return 0;
}